The present invention relates to electromagnetically stirring molten metal in a machine for continuous casting.
Generally speaking, stirring and-here particularly-electromagnetic stirring of the not yet solidified metal in a casting is a common expedient. Stirring the interior of the casting is used to enhance the cooling and solidification process and to impede organized solidification and formation of unwanted texture in the crystallization. Moreover, upon stirring one can expect reduced liquation of additives and reduced porosity of the core of the casting as it is about to be established.
The devices used for stirring the still molten metal in a casting are either placed alongside the casting as withdrawn from a mold, or the stirring devices circumscribe this casting. It will be appreciated that for the purpose of adequate and efficient electrical coupling, one has to place the stirring device, i.e., the electromagnetic energizing means, as close to the surface of the casting as possible.
The stirring devices referred to above are, necessarily, part of the equipment and machine to be installed before casting begins. Moreover, the requisite proximity to the casting requires that the position of the stirring device must be rather accurately predetermined and set in relation to the mold cavity. This means that the stirring device as mounted in the machine is directly tied to the format and cross section of the casting. A different mold and, particularly, a differently contoured and dimensioned mold cavity in the same machine requires a completely new installation of the stirring device, particularly if placed alongside the casting. A stirring device that circumscribes the casting is actually designed and rated for one type of casting as far as dimensions are concerned and may not be usable at all for other casting dimensions.